The general focus of this Program is a study of myocardial contractile mechanisms and their regulation. These studies are conducted along three avenues. The first, directed by Dr. Langer is concerned with the ion exchange characteristics of heart cells with a primary concern for exchange and binding characteristics of the heart cell coat and cellular ion exchange in ischemic and anoxic cardiac tissue. The second avenue is directed by Dr. Brady and involves studies of membrane excitation and conduction processes of heart cell and the mechanical and chemical kinetics of myocardial contraction. The third avenue directed by Dr. Homsher used skeletal muscle as its principal tool but is concerned with energetics of muscle metabolism, i.e. the conversion of chemical to mechanical energy.